Synthesis of crystal violet

ABSTRACT

A triphenyl methane dye, particularly crystal ciolet, is synthesized by reacting an aniline, particularly N, N-dimethyl aniline, with a carbon tetrahalide, particularly carbon tetrachloride, in the presence of aluminum chloride as a catalyst.

United States Patent Lohmann, Jr.

[ 1 Sept. 5, 1972 [54] SYNTHESIS OF CRYSTAL VIOLET [72] Inventor: Y George Y. Lohmann, Jr., 110 Bidwell Parkway, Buffalo, NY. 14222 [22] Filed: Sept. 4, 1969 [21] Appl. No.: 855,359

52 U.S. Cl. ..'..260/391 1,402,195 1 l 922 Trumbull ..260/39l Primary Examiner-Lorraine A. Weinberger Assistant Examiner-L. Arnold Thaxton Attorney sommer & Weber [57] ABSTRACT A triphenyl methane dye, particularly crystal ciolet, is synthesized by reacting an aniline, particularly N, N- dimethyl aniline, with a'carbon tetrahalide, particularly carbon tetrachloride, in the presence of aluminum chloride as a catalyst.

2 Claims, No Draivings SYNTHESIS OF CRYSTAL VIOLET BACKGROUND OF TI-IE INVENTION C0, with N, N-dimethyl aniline, PhNMe in the presence of phosphorous oxychloride, POCl P. Karrer, Berichte, 50, 1497 (1917);

2. adding chloropicrin to PhNMe heating the reaction mixture to 100C. and using aluminum chloride, AlCl as a catalyst, H.L. Trumbell et al., US. Pat. No. 1,402,195 (1922);

3. pouring 7 parts phosgene, (COCI gradually into a solution of one part Al Cl and 10 parts PhNMe I.N. Postovski; J. Chem. Ind. (Moscow), 4, 552 (1927);

4. condensing pbromoaniline, BrC H Nl-I with dimethylaminobiphenyl, [CH NC H OH, in the presence of sodium, Na, Morton et al., US. Pat. No. 2,029,830(1936); and

5. mixing phenyl sulfonyl chloride, PhS0 Cl, and PhNMe in bomb tubes, Harner and Nickel, Amm., 597, -47 1955). The principal difliculty with these processes is that they are both time consuming and expensive.

SUMMARY OF THE INVENTION cally synthesizing a triphenyl methane dye having the general formula with a carbon tetrahalide having the general formula CX, in the presence of aluminum chloride as a catalyst,

and thereafter separating the dye from the reaction mixture. The reaction proceeds according to the overall equation:

a possible mechanism for which is as follows:

ex. A1013 0x; maint AlCla ox mcnx The end products of the foregoing reaction are the following dye salts, which are either bromides or chlorides depending upon whether CBr, or CCL is employed: pararosaniline from aniline; trimethyl pararosaniline from N-methyl trimethyl pararosaniline from N-methyl, N-ethyl aniline; hexaethyl pararosaniline (ethyl violet) from N, N-diethyl aniline, and hexarnethyl pararosaniline (crystal violet or CV) from N, N-dimethyl aniline. These dyes then may be separated from the reaction mixture by any suitable known procedure.

aniline; triethyl, I

DESCRIPTION OF THE PREFERRED wherein the reactants are N, N-dimethyl aniline and EMBODIMENT carbon tetrachloride. The latter is particularly beneficial because it is not only highly reactive with the While the inventive roc il' p ess fac "ates the synthesls aniline to minimize the reaction time, but also readily of each of the above triphenyl methane dyes, it is par- 5 bl How cost ticularly adapted to quickly and economically synthesi e a dsi accordance with the overall ize crystal violet. Accordingly, in the preferred specific 5 f pmcee n embodiment of the invention, the dye formula equa becomes: CCl +3C H N(CI-I AlCl C(C H N[CH );,C-l

GEL/CH3 I which also may be written as:

CC| '+3PhNMe AlCl C(PhNMez)3Cl+ 3HCI CH1 i N@( JCl g I C a and is carried out at a temperature in the range from about C. to about C. for a time of not morethan about 30 minutes, with at least about 1 mole of CCl and at least about one-half mole of AlCl being em ployed for about 3 moles of PhNMe The possible CH: CH; mechanism for the reaction is as follows:

col. A101: 0013 M014 C =i3 C149 I /CH3 chc--N HG] A101:

(2) /CHa /G.Ha

c1,o-n 3, Clz0- N\ AlCli CHa- 0H,;

/CH3 6H /CHa CH3 cm \N-\C c1, 1101 A101,

NQCCl 1101+ A101: (0

The foregoing synthesis for CV was discovered while attempting to synthesize N, N-dimethyl aminotriphenyl chloride, in accordance with the following examples.

EXAMPLE I To 5 gms. (.05 mole) of AlCl and 15.3 gms. (0.1 mole) of CCL, which were heated to 70C. was slowly added 36.3 gms. (0.3 mole) Pl-lNMe,. After all the PhNMe was added, the reaction mixture was heated at 7080C. foran additional minutes, stirring continuously until the reaction was complete in a total time of not more than'about -30 minutes. The reaction mixture was poured onto 40 gms. of crushed ice, with the CVgoing into the aqueous layer. The organic layer was washed until it was no longer blue, .the total amount of water used being about 100 mls.

After washing the aqueous layer with ether to remove any traces of reactant, the aluminum salts were removed by precipitation with sodium bicarbonate as Al(0l-l) The solution then was boiled to dryness, the CV redissolved in ethanol, filtered, and recrystallized from the ethanol by adding ether. Gold-green crystals were obtained and proven to be CV by ultra violet spectrophotometry.

EXAMPLE II N Rl Ra wherein R and R, are members of the group consisting of hydrogen, methyl and ethyl, including the steps of reacting an aniline of the general formula with carbon tetrachloride in the presence of aluminum chloride as a catalyst, the reaction proceeding according to the overall equation:

and being carried out at a temperature. of at least about 50C. for a time of not more than about 30 minutes, and thereafter separating said dye from the reaction mixture.

2. The process of synthesizing crystal violet having the formula including the steps of reacting N, N-dimethyl aniline with carbon tetrachloride in the presence of aluminum chloride as a catalyst, the reaction proceeding according to the overall equation:

and being carried out at a temperature. in the range from about 50C. to about C. for a time of not more than about 30 minutes.

UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION Patent No. 3,689,495 Dated September 5, 1972 Inventor(s) George Y. Lohmann, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In ABSTRACT, first line, "ciolet" should read violet- Column 2, line 21, "(D (second occurrence) should read G) Column 4, line 11, ".+3HCl should read +3HCl-.

Column 5, line 8, "PHNMe should read -PhNMe Column 5, line l0 insert after "80".

Column 6 line l6, Claimv l, 2C1" should read Cl--.

Column 6 line 5 4, omit the period and insert and thereafter separating said crystal violet from the reaction mixture..

Signed and sealed this 8th day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCI'IER,JR. ROBERT GOTTSGHALK 4 Attesting Officer Commissioner of Patents FORM PO-1 (1069) USCOMM-DC sows-ps9 fi U,S, GOVERNMENT PRINTING OFFICE: [969 0-365-334 

2. The process of synthesizing crystal violet having the formula 